Water solvated glass/amorphous solid ionic conductors

ABSTRACT

The disclosure provides a water-solvated glass/amorphous solid that is an ionic conductor-an electronic insulator, and a dielectric as well as electrochemical devices and processes that use this material, such as batteries, including rechargeable batteries, fuel cells, capacitors, electrolysis cells, and electronic devices. The electrochemical devices and products use a combination of ionic and electronic conduction as well as internal electric dipoles.

PRIORITY CLAIM

The present application claims priority under 35 U.S.C. § 119 to U.S.Provisional Patent Application Ser. No. 62/181,606 filed Jun. 18, 2015and U.S. Provisional Patent Application Ser. No. 62/189,865 filed Jul.8, 2015, the contents of which are incorporated by reference herein intheir entirely.

TECHNICAL FIELD

The disclosure provides a dried, water-solvated glass/amorphous solidthat is an alkali-ion conductor and an electronic insulator with a largedielectric constant. The disclosure also provides electrochemicaldevices and processes that use this material, such as batteries,including rechargeable batteries, fuel cells, capacitors, electrolyticgeneration of chemical products, including hydrogen gas (H₂), fromwater, and electronic devices. The electrochemical devices and productsuse a combination of ionic and electronic conduction. The disclosurealso provides a water-solvated glass/amorphous solid that is a proton(IT) conductor and an electronic insulator.

BACKGROUND

Ionic conductors that are also electronic insulators are calledelectrolytes; they may be a liquid or a solid. Electrolytes are used ina variety of electrochemical devices, including not only those thatstore electric power as chemical energy in a rechargeable battery orthose that release chemical energy as electric power in a fuel cell, butalso those that store electric power as static electric energy in anelectric-double-layer capacitor. Electric power that is released from anelectric-energy store, whether from a chemical or an electrostaticstore, is clean energy. Chemical energy stored in a fuel that isreleased as the heat of combustion is a less efficient process, andcombustion is also accompanied by the release of gases that pollute theair and contribute to global warming.

An electrochemical cell contains an electrolyte between two electrodes,an anode and a cathode. A liquid electrolyte requires use of a separatorof the two electrodes that is permeable by the liquid electrolyte; theseparator prevents electronic contact between the two electrodes withinthe cell. A solid electrolyte may serve as both an electrolyte and aseparator. In a rechargeable battery, the anode is a reductant; in afuel cell, the anode catalyzes the separation of a reductant fuel intoits electronic and ionic components. In both types of cells, the ioniccomponent of the chemical reaction between two electrodes is transportedto the cathode inside the cell in the electrolyte, but the electrolyteforces the electronic component to go to the cathode via an externalcircuit as an electronic current I at a voltage V to provide electricpower P=IV for performance of work. Since the ionic conductivity in theelectrolyte is much smaller than the electronic conductivity in a goodmetal, battery cells and fuel cells are fabricated with large-areaelectrodes and a thin electrolyte; the active electrode materials arefabricated to make electronic contact with a metallic current collectorfor fast transport of electrons between the active electrode particlesand the external circuit as well as ionic contact with the electrolytethat transports ions between the electrodes inside the cell.

Solid electrolytes with a large dielectric constant may also be used inelectronic devices as separators of liquid or gaseous reactants as wellas of solid reactants.

Liquids are generally much better ionic conductors at room temperaturethan most known solids, which is why liquids are normally used as theelectrolyte of a room-temperature device. However, in some applicationsa solid electrolyte may be strongly preferred. For example, the Li-ionrechargeable battery uses a flammable organic liquid as the electrolyte,and a solid electrolyte would be safer and might be capable of improvingthe density of energy stored without sacrificing the rate of charge anddischarge. Moreover, if the solid electrolyte also contains electricdipoles that give it a high dielectric constant, it can store much moreelectric energy than a liquid in an electric capacitance of an electricdouble layer of a metal/electrolyte interface.

In an electric-double-layer capacitor, metallic electrodes arefabricated so as to provide a maximum electrode/electrolyte interface.Ions in the electrolyte pin electrons or electron holes of oppositecharge in the electrode across an electric double layer on charge. Theseparation of the electrons and holes across the double layer is small(atomic dimension) so the capacitance is large. On discharge, pinnedelectrons at the anode pass through the external circuit to recombinewith the pinned electron holes in the cathode, and the mobile ionsinside the electrolyte return to an equilibrium position. If theelectrolyte has a large dielectric constant the capacitance of theelectric double layer is enhanced. With a solid electrolyte having alarge dielectric constant, the enhancement of the capacitance is large,and it becomes possible to construct a cell where the energy stored hasa Faradaic component as in a battery and a capacitive component as in anelectric-double-layer capacitor.

SUMMARY

The present disclosure includes a dried, water-solvated glass/amorphoussolid electrolyte that conducts either Li⁺ or Na⁺, or both, nearly asrapidly as a flammable organic liquid at room temperature and also has alarge dielectric constant. Moreover, alkali metals can be plated andstripped from/to it without dendrite formation, thus avoiding safetyissues and a limited charge/discharge cycle life. A dried,water-solvated glass/amorphous solid that conducts Li⁺ may be referredto herein as a “Li-glass.” A dried, water-solvated glass/amorphous solidthat conducts Na⁺ may be referred to herein as a “Na-glass.”

The present disclosure includes a water-solvated glass/amorphous solidelectrolyte that conducts H⁺ and may be referred to herein as a “protonelectrolyte.”

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete understanding of the present embodiments and advantagesthereof may be acquired by referring to the following description takenin conjunction with the accompanying drawings, which relate toembodiments of the present disclosure.

FIG. 1 is a graph comparing Arrhenius plots of Lithium-ion (Li⁺)conductivity (σ_(Li)) versus temperature of a polymer gel with a salt,LiPF₆, and that of a Li-glass formed from precursor lithium hydroxides,LiOH, chlorides, LiCl and solvated water (H₂O); the solid was driedbefore measurement. The conductivity of AgI is also shown.

FIG. 2 is a graph showing the dependence on temperature, closed circles,and time at 25° C., open circles, of the Na⁺ conductivity, σ_(Na), of aNa-glass.

FIG. 3 is a graph showing the temperature dependence of the relativepermittivity (ε=ε′iε″) measured in an ac field of frequency f=1000 Hz,of a Li-glass obtained from a precursor composition of nominalLi₂₉Ba_(0.005)ClO. ε′ is the dielectric constant.

FIG. 4A is an Arrhenius plot showing the temperature dependence of theproton (H⁺) conductivity (σ_(H)) of a proton electrolyte solid obtainedby solvating water in BaKPO₄.

FIG. 4B is a graph showing a representative Nyquist plot taken at 25° C.of the frequency dependence of σ_(H) of a proton electrolyte; theimpedance is Z=Z′+iZ″.

FIG. 5 is a graph showing the charge/discharge cycling of a capacitorformed by a thick, Li-glass electrolyte sandwiched between two aluminumplates.

FIG. 6 is a schematic diagram of the ordering with time, pressure,and/or temperature of electric dipoles in an ac or dc electric field.

FIG. 7 is a graph showing charge/discharge curves of a full lithium cellshowing plating/stripping of a metallic lithium anode from a Li-glasselectrolyte.

FIG. 8 is a graph showing charge/discharge voltages of a full sodiumcell showing plating/stripping of a metallic-sodium anode from aNa-glass electrolyte.

DETAILED DESCRIPTION

The present disclosure relates to a water-solvated glass/amorphous solidthat conducts monovalent cations such as Li⁺, Na⁺, or H⁺, and mixturesthereof, and is an electronic insulator. If the water-solvatedglass/amorphous solid conducts Li⁺, Na⁺, or mixtures thereof, it isdried; an H⁺ conductor is not dried. The Li-glass and Na-glass areexcellent conductors of Li⁺, Na⁺ or mixtures thereof, and have highdielectric constants because of the presence of electric dipoles. Theyalso have a large enough electronic-state energy gap not only to beexcellent electronic insulators, but also to allow plating ofalkali-metal anodes and the use of high-voltage cathodes in alkali-metalrechargeable batteries that contain the dried water-solvatedglass/amorphous solid as the electrolyte or separator; electrochemicalcapacitors of high electrical-storage capacity can also be made with theLi-glass or Na-glass as the electrolyte. They are wet by the alkalimetal to allow plating and stripping of alkali-metal anodes withoutdendrite formation, and they are capable of high-voltage storage ofelectrostatic energy at a glass/metal interface. The materials can beformed as a paste for facile application to a large surface area. Theycan be used as the electrolyte and/or separator of a battery, fuel cell,or electrolysis cell and/or as a material in a capacitor of anelectronic device.

The disclosure also includes a method of forming the water-solvatedglass/amorphous solid electrolyte from constituent precursors containingat least one alkali metal atom, particularly lithium (Li) and/or sodium(Na), with oxygen and/or at least one halide atom, particularly chlorine(Cl), bromine (Br), iodine (I), or mixtures thereof, and water (H₂O)added in an amount less than or equal to the solvation limit of theglass/amorphous product. For example, the constituent precursors of theglass/amorphous product may include A_(3-x)H_(x)OX, AX+A₂O, or 2AOH+AX(H₂O) with x≤1 where A is an alkali metal such as Li and/or sodium Na ora mixture thereof and X a halide atom. The constituent precursor mayalso contain an oxide or hydroxide promoter of glass formation such asBa(OH)₂, Sr(OH)₂, BaO, SrO, CaO, MgO, Al₂O₃, B₂O₃, or SiO₂ and apromoter in which sulfur replaces the oxygen. An alternative is to pressat an appropriate temperature the precursor oxide, hydroxide, halide,and any other additive, including H₂O, until it forms a glass.

In addition, the disclosure includes a method of drying thewater-solvated glass/amorphous product. The method makes use of twochemical reactions. First, the reaction H₂O+X⁻═(OH)⁻+HX↑, where HXevaporates as a gas, e.g. HCl, during heating to form theglass/amorphous product. Second, the reaction 2(OH)⁻=O²⁻+H₂O↑ exhaustssteam (gaseous H₂O) below the decomposition temperature of the glass.

Excess alkali ions (A⁺) can form three types of dipole to give a largedielectric constant: OH⁻, OA⁻, and A⁺ in an asymmetric glass anion site.Orientation of the dipoles at higher temperatures, e.g. 50<T<110° C., inan ac or dc electric field before cooling to room temperature may beused to optimize more rapidly the cation conductivity at roomtemperature.

The disclosure also includes a method of fabricating the driedglass/amorphous product as a thin electrolyte in a cell where itseparates two electrodes. The method includes breaking theglass/amorphous product into small pieces and an aprotic liquid, such asethylene carbonate (EC), added to aid compaction of the powder into adense film covering a current collector or an alkali metal anode that,on heating, reforms into a thin, dry glass/amorphous film with no grainboundaries.

Alternatively, the dry glass/amorphous product may be ground to smallparticles in an aprotic liquid such as ethanol to form a slurry or inkthat can be applied as a thin layer over a large area of arbitraryshape; by a convenient method such as doctor-blading, printing, or vapordeposition. The cell ensemble is then sealed by a sealant such as Epoxythat cures exothermally and remains permeable to the evaporating gasfrom the liquid of the slurry while it is wet, but becomes impermeableas a solid sealant once it dries. Alternatively, the glass may be driedin a dry room. During evaporation of the liquid of the slurry, theglass/amorphous particles reform without grain boundaries into acontinuous sheet as a Li-glass or Na-glass electrolyte having a largedielectric constant owing to the presence of electric dipoles.

The disclosure also includes a water-solvated glass/amorphous proton(H⁺) electrolyte formed by solvating water into a crystalline solidcontaining a strongly electropositive cation such as a large alkali ionlike that of potassium (K⁺), rubidium (Rb⁺), or cesium (Cs⁺) and astrongly acidic polyanion such as (SiO₄)⁴⁻, (PO₄)³⁻, or (SO₄)²⁻. Thesolvated water, H₂O, is captured by the strongly electropositive cationsas an (OH)⁻ ligand with the release of the H⁺ ion, which is mobile inthe presence of the solid polyanions. This process transforms thecrystalline parent compound into a proton electrolyte.

The disclosure includes a water-solvated glass/amorphous solid producedby any of these methods.

The disclosure also relates to a paste including particles of a Li-glassor N-glass as described above in an organic liquid, an ionic liquid,and/or a polymer.

The disclosure further includes dielectric electrolytes-formed from awater-solvated glass/amorphous solid or paste as described above.

The disclosure additionally includes a method of forming a dielectricelectrolyte by forming a paste as described above, applying the paste toa surface, and allowing some or all of the organic liquid, ionic liquid,and/or polymer to evaporate, leaving a reformed electrolyte dielectric.The disclosure includes the electrolyte-dielectric thus formed.

A water-solvated, dried glass/amorphous alkali-ion electrolyte having alarge dielectric constant that may be used in an electrochemical cellthat stores electric power as in a rechargeable battery, a cell thatstores electric power as static electricity in the capacitances of anelectric double layer at a metal/electrolyte interface, a cell thataccomplishes both types of electric-power storage in the same cell, or acell that is used in an electronic device.

Electrolyte/Dielectric Material

The water-solvated dried glass/amorphous solid may be formed from acrystalline electronic insulator or its constituent precursors (e.g.LiCl+2Li(OH)+xBa(OH)₂.8H₂O) by the addition of water (H₂O) up to thesolubility limit of the crystalline electronic insulator. Water issolvated into the crystalline electronic insulator by separation of thehydroxide (OH) anion from the proton. Where this separation occurs, thesolvated water acts like a salt dissolved in a liquid. The separation ofthe hydroxide anion and the proton may be stabilized by trapping theproton by an X⁻ ion with the escape of HX gas; and mobile OH⁻ ions mayreact with one another to form H₂O that leaves the solid at highertemperature. The separation of the H⁺ and (OH)⁻ ions may also beachieved by the trapping of OH⁻ anions at a large, stronglyelectropositive atom like Ba²⁺, K⁺, Rb⁺, Ca⁺ with the release of the H⁺ion to an acidic matrix.

If a halide (X⁻) anion, such as a chloride (Cl⁻) anion, a bromide (Br⁻)anion, and/or an iodide (I⁻) anion, is also present in the crystallineelectronic insulator, the proton can combine with the X⁻ anion anddepart from the solid as a hydrogen halide (HX) gas, with the hydroxideanion remaining in the solid. The mobile OH⁻ ions may react with oneanother to form O²⁻ and H₂O with the water leaving the solid at highertemperatures. The departure of the proton (H⁺) and water from thewater-solvated glass/amorphous solid means that the product is dry andcan be used to contact an alkali-metal anode in a battery or in otherelectronic devices sensitive to the presence of water. If the hydroxideanions are not trapped in a hydrated polyanion such as Ba(OH)_(x)^((2-x)), they are mobile, as are any alkali cations, such as lithiumion (Li⁺) and/or sodium ion (Na⁺), of the-electronic insulator. Thelithium ion (Li⁺) and/or sodium ion (Na⁺) are much more mobile than theOH⁻ anions. Nevertheless, the mobile (OH)⁻ ions may react as2(OH)⁻═O²⁻+H₂O↑ with the escape of steam at higher temperatures.

Alternatively, if a large cation like the barium ion (Ba²⁺) or potassiumion (K⁺) rubidium (Rb⁺), or cesium (Cs⁺) is present in a crystallineelectronic insulator, the hydroxide (OH⁻) anion of the solvated water(H₂O) may be trapped in a-polyanion of the large cation and the proton(H⁺) may be mobile if the other anion of the crystalline electronicinsulator is a strongly acidic polyanion like phosphate (PO₄)³⁻ orsulfate (SO₄)²⁻. Most of the protons (H⁺) are not trapped by thepolyanions or in a hydrogen bond so long as the solvated water hastransformed the crystalline electronic insulator into a water-solvatedglass/amorphous solid.

The finished water-solvated glass/amorphous solid may be derived fromany crystalline electronic insulator or its mix of oxide, hydroxide,and/or halide constituent precursors that can be transformed into aglass/amorphous solid by the solvation of water into it with or withoutthe aid of an oxide, sulfide, or hydroxide additive. If the originalcrystalline material contains a large concentration of alkali ionsbonded to oxide and/or halide ions, it may be transformed into a fastconductor of lithium ion (Li⁺) and/or sodium ion (Na⁺) and an electronicinsulator by drying at high temperatures. If the crystalline electronicinsulator contains only acidic polyanions and large, electropositivecations that stabilize hydroxide polyanions, transformation to awater-solvated glass/amorphous solid by the solvation of water providesa fast proton (H⁺) conductor.

The water used to form a Li-glass or Na-glass may include less than twomole percent water and less than one mole percent of a glass-formingadditive. The glass-forming additive may aid the transformation of thecrystalline electronic insulator into a dried water-solvatedglass/amorphous solid. The glass-forming additive may include at leastone oxide, sulfide, and/or hydroxide, such as barium oxide (BaO),magnesium oxide (MgO), calcium oxide (CaO) and/or barium hydroxideBa(OH)₂, Mg(OH)₂, Ca(OH)₂, Sr(OH)₂, or Al(OH)₃, BaO, SrO, CaO, MgO, Al,B₂O₃, Al₂O₃, SiO₂, S or Li₂S, and mixtures thereof. The water-solvatedglass/amorphous solid has a glass transition temperature, T_(g), thatcan be adjusted by the character of the cation that is introduced intothe crystalline electronic insulator or its constituent precursor topromote glass formation. In addition, the hydroxide (OH⁻)⁻ anions of thedried water-solvated glass/amorphous solid or any other electric dipolelike (OH)⁻ or (OA)⁻ where A=Li or Na, or an A⁺ ion in an asymmetricglass site may be oriented in an ac or dc electric field to enhance thedielectric constants and the cation conductivity.

The water-solvated glass/amorphous solid may be ground into a pluralityof small pieces and mixed with a polymer, an ionic liquid, and/or anorganic liquid such as ethanol that evaporates quickly or ethylenecarbonate (EC) in order to form a paste for easy application over alarge surface area before reforming into a glassy amorphous solid. Thisprocess may improve contact with a solid electrode and/or currentcollector. Upon evaporation of some or all of the liquid component, theglass/amorphous solid is reformed as a large-volume ionic conductor withfew, if any, grain boundaries. Evaporation may occur prior to inclusionin an electrochemical device or afterwards.

Two specific processes illustrate the transformation of the constituentprecursor of a crystalline electronic insulator into a water-solvatedglass/amorphous solid that is an ionic conductor and electronicinsulator that is dry.

(1) The constituent precursor oxides, hydroxides, and halides of thecrystalline electronic insulator may have the general formula A₃₋₁⁺H_(x) ⁺, wherein 0≤x≤1 and A is lithium (Li) and/or sodium (Na) andwherein X is chlorine (CO, bromine (Br), and/or iodine (I). Thisstarting material is rich in alkali ions bonded to only oxide and halideanions. Addition of water up to the solubility limit of the water withor without the addition of an oxide and/or hydroxide such as bariumoxide (BaO), magnesium oxide (MgO), and/or barium hydroxide (Ba(OH)₂)transforms the crystalline electronic insulator or constituent precursorto a dry water-solvated glass/amorphous solid that is a lithium ion(Li⁺) and/or sodium ion (Na⁺) ionic conductor that remains an electronicinsulator. The glass transition temperature decreases with an increaseof the size of the cation of the added oxide and/or hydroxide; with thebarium ion (Ba²⁺) and lithium ion (Li⁺), a T_(g)≈55° C. is obtained.

In one example, the constituent precursors of the crystalline materialLi_(3-x)H_(x)OCl contained an added 0.005 Barium oxide (BaO) per formulaunit. Hydrogen chloride (HCl) gas left the solid during amoderate-temperature anneal of the water-solvated glass/amorphous solid.Hydroxide (OH⁻) anion conductivity was also observed, but was muchsmaller than lithium ion (Li⁺) conductivity, and above 230° C., a weightloss signaled the occurrence of the reaction 2(OH)⁻═O²⁻+H₂O↑ as a resultof the evaporation of the water (H₂O). FIG. 1 illustrates lithium ion(Li⁺) conductivity as a function of temperature in an Arrhenius plot forthis material. FIG. 3 presents the variation of the dielectric constantof this material with temperature.

FIG. 2 illustrates sodium ion (Na⁺) conductivity as a function oftemperature in an Arrhenius plot for a water-solvated glass/amorphoussolid in which sodium (Na) replaced (Li) in the constituent precursorfor Na_(3-x)H_(x)OCl to which 0.005 Barium oxide (BaO) per formula unitwas added. Hydrogen chloride (HCl) gas left the solid during amoderate-temperature anneal of the water-solvated glass/amorphous solid.Hydroxide (OH⁻)⁻ conductivity was also observed, but was much smallerthan the sodium ion (Na⁺) and above 230° C., a weight loss signaled thereaction 2(OH)⁻═O²⁻+H₂O↑ which dried completely the glass/amorphousproducts.

Water-solvated glass/amorphous solid sodium-ion (Na⁺) and lithium-ion(Li⁺) conductors have been used to plate reversibly metallic sodium (Na)or metallic lithium (Li) onto itself without dendrites over 1000 times,thereby proving that a dry water-solvated glass/amorphous solid can beused in a rechargeable sodium-ion or lithium-ion battery and thatsimilar dry materials can be used in other batteries or water-sensitivedevices.

(2) KH₂PO₄ is a crystalline ferroelectric in which the protons (H⁺) aretrapped in hydrogen bonds. However, BaKPO₄ is a crystalline electronicinsulator containing large barium ions (Ba²⁺) and potassium ions (K⁺)ions that can stabilize hydroxide polyanions if exposed to water vapor.Solvation of water into this solid creates a water-solvatedglass/amorphous solid that is a fast H⁺ conductor and an electronicinsulator.

FIG. 4 presents an Arrhenius plot of the proton (H⁺) conductivity of thewater-solvated glass/amorphous solid derived from BaKPO₄ by exposure towater vapor at 80° C. Note that the proton conductivity is σ_(H)=10⁻² Scm⁻¹ at a T≈75° C., which makes it possible to use it as a replacementfor a NAFION membrane in a room-temperature fuel cell or a rechargeablebattery with a redox-couple flow-through liquid electrode.

Electrolytes

The magnitude of the ionic conductivity of an electrolyte in anelectrochemical cell dictates the thickness and area of the electrolyteseparating the two electrodes for a desired output current I. The energydifference E_(g) between the lowest unoccupied molecular orbital (LUMO)and the highest occupied molecular orbital (HOMO) of the electrolytedictates the highest voltage V for stable operation of a cell.Therefore, the electric power on charge and discharge,P_(ch)=I_(ch)V_(ch) and P_(dis)=I_(dis)V_(dis), depends critically onthe electrolyte as also does the efficiency of storage of electricalenergy, 100 P_(dis)/P_(ch) %. The voltages of a cell are

V _(ch) =V _(oc)+η_(ch)(I _(ch)) and V _(dis) =V _(oc)−η_(dis)(I_(dis))  (1)

where the voltage at open electronic circuit is V_(oc)=(μ_(A)−μ_(C))/e;the μ_(A) and μ_(C) are, respectively, electrochemical potentials of theanode and the cathode, and e is the magnitude of the electronic charge.

The η_(ch) and η_(dis) are called, respectively, the overvoltage and thepolarization. The η(q)=IR_(cell) depend on the resistancesR_(cell)=R_(el)+R_(ct); R_(el) is the resistance to the ionicconductivity σ_(i)=n_(i)q_(i)μ_(i) in the electrolyte and R_(ct) is theresistance to ionic transport across any electrode/electrolyteinterfaces. The mobility μ_(i)=v/E is the velocity of the ion in anapplied electric field E. The R_(ct) at the anode and the cathodeinterface with the electrolyte are different from one another and thecharge transport across an interface is also different between chargeand discharge, so η_(ch)≠η_(dis).

The capacity of a rechargeable battery is the amount of charge per unitweight or volume passed between the electrodes during a completereaction at a constant current I=dq/dt:

Q(I)=∫₀ ^(dt) Idt=∫ ₀ ^(Q(t)) dq  (2)

An irreversible capacity loss in a charge/discharge cycle, i.e. aΔt_(dis)(n+1)<Δt_(dis)(n), where (n+1) and n are cell cycle numbers,represents a capacity fade with cycling. The coulombic efficiency of thecell 100Δt_(dis)(n+1)/Δt_(dis)(n) % is a measure of the cycle lifebefore a rechargeable battery capacity fades to 80% of its originalcapacity.

The energy density of a rechargeable battery is

ΔE=∫ ₀ ^(Δt)IVdt=∫₀ ^(Q(t)) V(q)dq=<V(q)>Q(I)  (3).

where Q(I) is the capacity at a current I defined by equation (2).

For a given chemical reaction between the two electrodes of arechargeable electrochemical cell, a small R_(el) requires a thinelectrolyte with a sufficient density n_(i) of mobile working ionscarrying a charge q_(i) with a high mobility μ_(i). The electronicconductivity of a highly conductive metal is orders of magnitude greaterthan any electrolyte ionic conductivity σ_(i)=n_(i) q_(i) μ_(i), sorechargeable batteries are typically fabricated with a thin electrolytebetween electronically conducting electrodes that have a large area, butthe electrodes need not-have a high electronic conductivity so long asthey are not too thick and make electronic contact to a large-area,metallic current collector.

The R_(ct) can be made small across a solid/liquid interface, but it isincreased where a mismatch between the μ_(A) or μ_(C) of a solidelectrode and the LUMO or HOMO of a liquid electrolyte requiresformation of a passivating solid-electrolyte-interphase (SEI) layer thatmust allow transfer of the working ion across it also. For gaseousreactants at a solid-electrolyte surface, R_(ct) may be low if it isaccompanied by a high catalytic activity for the dissociation of the gasand its chemisorption into the electrolyte or the extraction of the gasfrom the electrolyte. A low R_(ct) across a solid/solid interface isalso critical. Even at an alkali-metal anode where plating only changesthe electrode dimension perpendicular to the interface, a soft polymerinterface layer that is chemically stable on contact with the two solidsmay be useful to maintain a long cycle life. If the electrode includessmall particles into which the working ion is inserted, displaces anatom, or forms an alloy, the particle changes volume. This volume changenormally prevents the solid/solid interface from being maintained duringcycling. This problem occurs even if the solid electrolyte is made intoa paste or a melt during fabrication to wet all the surfaces of theelectrode particles. This problem limits the battery capacity and cyclelife of previous all-solid-state batteries. However, realization ofreversible plating of an alkali metal across the solid/solidalkali-metal/-glass electrolyte interface allows optimization of thecell voltage for a given cathode and eliminates losses associated withan anode SEI layer. Moreover, a solid electrolyte blocks soluble speciesof a liquid redox-molecule flow-through cathode or soluble intermediatesof a sulfur cathode from reaching the anode. However, traditional solidelectrolytes, whether glassy, amorphous, or crystalline, do not have theionic conductivity needed to allow their use at ambient temperatureunless they are so thin that they need to be supported by a poroussubstrate or sandwiched between polymer-electrolyte membranes, and theearly report of a glass formed from a crystalline lithium conductor didnot demonstrate why it could be dry or what ionic species was thedominant conductor. Moreover, it would be impossible to plate an alkalimetal on a copper current collector across the solid/solid interface inthe presence of liquid water in the electrolyte.

Since the water-solvated glass/amorphous solids obtained in thisdisclosure have a LUMO>E_(F)(Li) and are stable in organic liquid, ionicliquid, and/or polymer electrolytes, they may be used with a liquidcatholyte and/or polymer located between the solid electrolyte and thecathode and/or with a passivating solid-electrolyte interphase (SEI)layer and/or polymer between the anode and the solid electrolyte. Thedry water-solvated glass/amorphous electrolytes of this disclosure openup the possibility of using rechargeable batteries with a variety ofcathodes: conventional reversible insertion-compound solid cathodes,redox flow-through liquid cathodes, gaseous air cathodes, and solidsulfur cathodes. The use of a solid lithium-ion (Li⁺) or sodium-ion(Na⁺) electrolyte also allows a choice of a variety of electrochemicalcells, including fuel cells, electrolysis cells, and capacitor cells aswell as rechargeable battery cells.

The water-solvated glass/amorphous solid proton electrolytes formed byexposing crystalline BaKPO₄ to water vapor can replace the NAFIONmembrane in an ambient temperature fuel cell.

Rechargeable batteries containing a water-solvated glass/amorphous solidelectrolyte described herein can provide a safe, low-cost stationarybattery capable of storing a large amount of electrical energy forfeeding the grid or charging the battery or capacitor of an electricvehicle since the temperature range of operation of a stationary batterycan be kept small through all seasons at little cost. The smallactivation energy for alkali-ion transport in the electrolyte can alsomake feasible an electric vehicle powered by a portable rechargeablebattery that operates in a wide range of ambient temperatures.

Dielectrics

The water-solvated glass/amorphous solids described herein provide hugedielectric constants that can be used in capacitors or other deviceswhere there is no ionic transport across the solid/solid interface of ametallic electrode and the solid electrolyte. The mobile ions move tothe interfaces to create an electric-double-layer capacitor and theelectric dipoles in the solid are free to rotate to add their dipolemoment to the dielectric constants. The temperature dependence of thedielectric constants are the same as or similar to those shown in FIG.3.

Capacitors, like batteries, store electrical energy; but unlike arechargeable battery or a reversible fuel cell, the energy is stored asthe electrostatic energy between electrons or electron holes in themetallic plates of a capacitor and dipoles or mobile ions in a solidelectrolyte that separates the two metallic plates. In a double-layerelectrochemical capacitor, mobile cations in the electrolyte attractelectrons to one plate and mobile and/or static anions attract electronholes to the opposing plate. The mobile ions of the electrolyte aretrapped by the electrons or electron holes in the metallic plates aslong as the charging external circuit is opened, preventing theelectrons and electron holes created by charging from recombining.However, on closing the electronic circuit, the electrons recombinequickly, thereby releasing ion flow and dipole rotation in theelectrolyte dielectric. FIG. 5 illustrates the charge/discharge cyclingof a capacitor formed by sandwiching a thick water-solvatedglass/amorphous solid between two aluminum plates. In the absence ofcarbon, the thin aluminum oxide (Al₂O₃) layer on the surface of thealuminum plates blocks charge transfer across the solid/solid interfaceto up to a 10 V charge. On discharge, there are three regions versustime, one within a second that was too fast to be recorded, one over oneto three seconds that was slow enough to be recorded with the apparatusused, and a slow third that lasts for several minutes. The fastestpresumably reflects electron transport between trapped electrons in theanode and electron holes in the cathodes, the intermediate discharge themovement of cations away from the interfaces resulting from the loss oftrapped electron charge, and the slow discharge any reorientation ordiffusion of the electric dipoles.

Ionic Conductors

Electronic conduction controls electronic devices. However, nature usesionic conduction and redox energies to accomplish many things. Thewater-solvated glass/amorphous solids of the present disclosure may beused in devices, methods, and systems that utilize both ionic andelectronic conduction. For instance, the trapping of electrons and/orelectron holes at metal/electrolyte interfaces may be used in anelectronic memory or switch. Exploration of the wedding ofelectrochemistry and electronic devices remains a relatively unexploreddomain.

According to a first embodiment, A, the disclosure provides a method offorming a dried, water-solvated glass/amorphous solid. The methodincludes transforming a crystalline, sodium ion (Na⁺) or lithium-ion(Li⁺) electronic insulator or its constituent precursors comprising atleast one Na⁺ or Li⁺ bonded to oxygen (O), hydroxide (OH), and/or to atleast one halide into a water-solvated glass/amorphous Na⁺ or Li⁺ion-conducting solid by adding water in an amount less than or equal tothe water solvation limit of the glass/amorphous solid.

In further embodiments, which may be combined with embodiment A and withone another unless clearly mutually exclusive, i) the method furtherincludes adding a glass-forming oxide, sulfide, or hydroxide and heatingto expel volatile constituents; ii) the crystalline, electronicinsulator or its constituent precursors include a material with thegeneral formula A_(3-x)H_(x)OX, wherein 0≤x≤1, A is the at least onealkali metal, and X is the at least one halide; iii) the crystalline,electronic insulator or its constituent precursors includes aglass-forming additive comprising at least one of an oxide, a hydroxide,and/or a sulfide; iv) the glass-forming additive includes at least oneof Ba(OH)₂, Sr(OH)₂, Ca(OH)₂, Mg(OH)₂, Al(OH)₃, or BaO, SrO, CaO, MgO,Al, B₂O₃, Al₂O₃, SiO₂, S and/or Li₂S; v) the additive includes at leasttwo of an oxide, a hydroxide, and/or a sulfide; vi) the additiveincludes at least two of Ba(OH)₂, Sr(OH)₂, Ca(OH)₂, Mg(OH)₂, Al(OH)₃, orBaO, SrO, CaO, MgO, Al, B₂O₃, Al₂O₃, SiO₂, S and/or Li₂S; vii) thedried, water-solvated glass/amorphous solid includes less than 2 molepercent of the glass-forming additive; viii) the additive adjusts theglass transition temperature T_(g) of the water-solvated glass/amorphoussolid; ix) the at least one halide includes chlorine (CO, bromine (Br)and/or iodine (I); x) at least a portion of the at least one halideexits the water-solvated glass/amorphous solid as a hydrogen halide gas;and xi) the hydroxide reacts to form H₂O that exits the water-solvatedglass/amorphous solid as gaseous H₂O.

According to a second embodiment, B, the disclosure provides a method offorming an H⁺-conductive water-solvated electrolyte. The method includestransforming a crystalline material comprising at least one alkaliand/or alkaline-earth cation bonded to at least one acidic polyanioninto a glass/amorphous solid by adding water in an amount less than orequal to its solvation limit in the crystalline material such that waterdissociates into hydroxide (OH)⁻ anions that coordinate to the cationsto form polyanions and the water also dissociates into protons (H⁺) thatare mobile in a framework of an acidic oxide and the polyanions.

According to a third embodiment, C, the disclosure provides a method offorming a water-solvated glass/amorphous solid. The method includestransforming a crystalline electronic insulator comprising at least oneacidic polyanion and at least one cation into a water-solvatedglass/amorphous proton (H⁺)-conducting solid by adding water in anamount less than or equal to the water solvation limit of thecrystalline electronic insulator

In further embodiments, which may be combined with embodiments B or C,and with one another unless clearly mutually exclusive: i) wherein theacidic polyanion includes (SO₄)²⁻ and/or (PO₄)³⁻ and/or (SiO₄)⁴⁻polyanion; ii) the at least one cation is stabilized in the form of atleast one stable hydroxide polyanion; iii) the at least one cationincludes a barium (Ba²⁺) ion, a potassium (K⁺) ion, a rubidium (Rb⁺)ion, and/or a cesium (Cs⁺) ion; iv) the stable hydroxide polyanionincludes (Ba(OH)_(x))^(2-x), (K(OH)_(x))^(1-x), (Rb(OH)_(x))^(1-x)and/or (Cs(OH)_(x))^(1-x).

According to a fourth embodiment, D, the disclosure provides awater-solvated glass/amorphous solid formed from the method of any ofthe above embodiments. The disclosure further provides, in additionalembodiments, electrolytes and dielectrics including this water-solvatedglass/amorphous solid

According to a fifth embodiment, E, the disclosure provides a paste orslurry including the dried water-solvated glass/amorphous solid ofembodiment D, wherein the paste or slurry includes particles of thewater-solvated glass/amorphous solid in an organic liquid, an ionicliquid, and/or a polymer. According to a further embodiment, the pasteor slurry may be applied to a large surface area by painting,doctor-blading, vapor deposition, or printing.

According to a sixth embodiment, F, the disclosure provides a method offorming an electrolyte or dielectric by applying the paste or slurry ofembodiment E to a surface. In further embodiments, the organic liquid,ionic liquid, and/or polymer may be allowed to evaporate totally or inpart, leaving an electrolyte or dielectric, or the organic liquid, ionicliquid, and/or polymer may not be allowed to evaporate.

According to a seventh embodiment, G, the disclosure provides a batteryincluding a material as described above. The battery may also include aliquid electrolyte, a polymer electrolyte, or a mixture thereof, whereinthe liquid or polymer electrolyte contacts at least one electrode in thebattery.

According to an eighth embodiment, H, the disclosure provides a cell forstoring electrical energy including a faradaic and a non-faradaiccomponent including an electrolyte material as described above.

According to a ninth embodiment, I, the disclosure provides a capacitorincluding a material as described above. The capacitor may include twoelectrodes formed from the same metal or metal alloy, or it may includetwo electrodes formed from two different metals or metal alloys havingtwo different Fermi energies.

According to a tenth embodiment, J, the disclosure provides a fuel cellincluding a material as described above. The fuel cell may bereversible.

According to an eleventh embodiment, K, the disclosure provides anelectrolysis cell including an electrolyte or separator including amaterial as described above. The electrolysis cell may produce hydrogengas (H₂) from water.

According to a twelfth embodiment, L. the disclosure provides anelectrochemical device including a reversible fuel cell of embodiment Jand a chemical storage bed.

According to a thirteenth embodiment, M, the disclosure provides anelectronic device including a material as described above. According tofurther embodiments, which may be combined with one another: i) theelectronic device includes a memory, a transistor, a switch, or a sensorincluding a material as described above; ii) the electronic device usesa piezoelectric effect of a material as described above; iii) theelectronic device uses a pyroelectric effect of a material as describedabove.

According to a fourteenth embodiment, N, the disclosure provides adevice that transforms heat into electric power at a fixed temperatureusing a material as described above

Although only exemplary embodiments of the disclosure are specificallydescribed above, it will be appreciated that modifications andvariations of these examples are possible without departing from thespirit and intended scope of the disclosure. For instance, numericvalues expressed herein will be understood to include minor variationsand thus embodiments “about” or “approximately” the expressed numericvalue unless context, such as reporting as experimental data, makesclear that the number is intended to be a precise amount. In addition,the water-solvated glass/amorphous solids may be used in batteries andcapacitors and other electrical or electrochemical devices havingcomponents and properties that are otherwise known and that aredescribed in the background.

1. A method of forming a dried, water-solvated glass/amorphous solid,the method comprising transforming a crystalline sodium-ion (Na⁺) orlithium-ion (Li⁺) electronic insulator or its constituent precursorscomprising at least one Na⁺ or Li⁺ bonded to oxygen (O), hydroxide (OH),and/or to at least one halide and at least less than one mole percentglass-forming additive into a water-solvated glass/amorphous Na⁺ or Li⁺ion-conducting solid by adding water in an amount less than two molepercent and heating to at least 230° C.
 2. (canceled)
 3. The method ofclaim 1, wherein the crystalline, electronic insulator or itsconstituent precursors comprise a material with the general formulaA_(3-x)H_(x)OX, wherein 0≤x≤1, A is the at least one alkali metal, and Xis the at least one halide.
 4. The method of claim 1, wherein theglass-forming additive comprising at least one of an oxide, a hydroxide,and/or a sulfide.
 5. The method of claim 4, wherein the glass-formingadditive comprises at least one of Ba(OH)₂, Sr(OH)₂, Ca(OH)₂, Mg(OH)₂,Al(OH)₃, BaO, SrO, CaO, MgO, B₂O₃, Al₂O₃, SiO₂, S and/or Li₂S.
 6. Themethod of claim 4, wherein the glass-forming additive comprises at leasttwo of an oxide, a hydroxide, and/or a sulfide.
 7. The method of claim6, wherein the glass-forming additive comprises at least two of Ba(OH)₂,Sr(OH)₂, Ca(OH)₂, Mg(OH)₂, Al(OH)₃, or BaO, SrO, CaO, MgO, Al, B₂O₃,Al₂O₃, SiO₂, S and/or Li₂S.
 8. (canceled)
 9. The method of claim 4,wherein the glass-forming additive adjusts the glass transitiontemperature T_(g) of the water-solvated glass/amorphous solid.
 10. Themethod of claim 1, wherein the at least one halide comprises chlorine(Cl), bromine (Br) and/or iodine (I).
 11. The method of claim 1, whereinat least a portion of the at least one halide exits the water-solvatedglass/amorphous solid as a hydrogen halide gas.
 12. The method of claim1, wherein the hydroxide reacts to form H₂O that exits thewater-solvated glass/amorphous solid as gaseous H₂O. 13-20. (canceled)